Natural This kind of functionality represents a partial function on naturals, in which the evidence of even (n) could be witnessed to be a precondition. Through the Cambridge English Corpus There is not any actual distinction between the standard to start with-order objects of your mathematical discourse - for instance https://medium.com/@cureayublog/cureayu-natural-healthcare-solutions-for-mind-body-balance-464977ee5d85?postPublishedType=initial